What was github written in
The big climber is of course Java: The programming language grew more than any other language between and GitHub attributes the big rank change, from seventh to second, due to growing Android popularity, which in turn results in demands for business and enterprise version control. Other noticeable trends can be explained by specifics to GitHub.
The trend line for Ruby on Rails, for example, is likely due to the fact the programming language has been on GitHub since The rank is represented by languages used in public and private repositories, excluding forks. It is calculated by a GitHub project called Linguist. Their names are fe1 , …, fe4. Nginx accepts the connection and sends it to a Unix domain socket upon which sixteen Unicorn worker processes are selecting.
One of these workers grabs the request and runs the Rails code necessary to fulfill it. Many pages require database lookups. Their names are db1a and db1b.
At any given time, one of them is master and one is slave. If the page requires information about a Git repository and that data is not cached, then it will use our Grit library to retrieve the data. We start by abstracting out every call that needs access to the filesystem into the Grit::Git object. Smoke has direct disk access to the repositories and essentially presents Grit::Git as a service. Get it? The stubbed Grit makes RPC calls to smoke which is a load balanced hostname that maps back to the fe machines.
ProxyMachine is my content aware layer 7 TCP routing proxy that lets us write the routing logic in Ruby. The proxy examines the request and extracts the username of the repository that has been specified. We then use a proprietary library called Chimney it routes the smoke!
Chimney finds the route by making a call to Redis. Redis runs on the database servers. We have four pairs of fileservers. Their names are fs1a , fs1b , …, fs4a , fs4b. At any given time one server in each pair is active and the other is waiting to take over should there be a fatal failure in the master. All repository data is constantly replicated from the master to the slave via DRBD.
Each Ernie spawns 15 Ruby workers. These workers take the RPC call and reconstitute and perform the Grit call. The response is sent back through the Smoke proxy to the Rails app where the Grit stub returns the expected Grit response. When Unicorn is finished with the Rails action, the response is sent back through Nginx and directly to the client outgoing responses do not go back through the load balancer. The above flow is what happens when there are no cache hits.
Since these machines are otherwise idle, we place 12GB of Memcache on each. These servers are aliased as memcache1 , …, memcache4. These are the exact libraries we use at GitHub to serve up all repository data.
Git uses SSH for encrypted communications between you and the server. In order to understand how our architecture deals with SSH connections, it is first important to understand how this works in a simpler setup. Git relies on the fact that SSH allows you to execute commands on a remote server.
For instance, the command ssh tom frost ls -al runs ls -al in the home directory of my user on the frost server. I get the output of the command on my local terminal. Site policy. You can structure the information shared on GitHub with various formatting options.
Getting started with writing and formatting on GitHub About writing and formatting on GitHub Basic writing and formatting syntax Working with advanced formatting Organizing information with tables Creating and highlighting code blocks Autolinked references and URLs Attaching files Creating a permanent link to a code snippet Using keywords in issues and pull requests Working with saved replies About saved replies Creating a saved reply Editing a saved reply Deleting a saved reply Using saved replies Editing and sharing content with gists Creating gists Forking and cloning gists.
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